1. Field of the Invention
The present invention relates to novel thermosetting compositions comprising certain imido prepolymers and an epoxy resin.
2. Description of the Prior Art
Thermosetting compositions comprising a bis-maleimide and N-vinyl-2-pyrrolidone are already known to this art; Belgian Pat. No. 846,365 (U.S. Pat. No. 4,111,919). Such compositions may be used in the prepolymer state for molding operations, either by casting or impregnation. Further, improvements in the properties of epoxy resins too are known to have been sought, by combining same with the derivatives of a polyimide of an unsaturated carboxylic acid. Compare the compositions described in, for example, French Pat. Nos. 2,045,087 and 2,076,447. The '087 French patent has for a major object the hardening or curing of epoxy resins by means of a prepolymer obtained by heating a bis-imide and a polyamine. The '447 French patent mentions the combination of an epoxy resin, a bis-imide and a carboxylic acid anhydride which, after hardening, yields materials having increased mechanical properties.
However, for certain applications it would be useful to provide compositions simultaneously having good stability at ambient temperature, greater fluidity at low temperatures than the imide prepolymers and adapted for the ultimate preparation of materials having excellent mechanical properties.